Alec Baldwin has launched a Twitter.com campaign in a bid to stop U.S. TV veteran David Letterman retiring from his long-running late night talk show. The Late Show host plans to step down from fronting the program in 2015, and the news came as a shock to big fan Baldwin. The actor has now launched a drive on Twitter to persuade Letterman to stay, urging fans to petition the TV host via the social networking website. He writes, “Maybe it’s futile, but here goes… Letterman cannot retire. Just… just…. no. Send him this: #DontGoDave.”